<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>实训1.使用判断验证变量的布尔值</title>
<script language="javascript" type="text/javascript">
var num1=10,num2;
alert("未赋值的变量布尔值为:"+Boolean(num1));
alert("赋值的变量布尔值为:"+Boolean(num2));
</script>
</head>

<body>
</body>
</html>
